/Engine/Plugins/Online/OnlineSubsystem/Source/Public/Interfaces/OnlineIdentityInterface.h
Converts from a local user num used by the online system to a PlatformUserId used by application code
The corresponding id or PLATFORMID_NONE if invalid
virtual [FPlatformUserId](API\Runtime\Core\Misc\FPlatformUserId) GetPlatformUserIdFromLocalUserNum ( int32 LocalUserNum ) const